CN103383490B - Optical scanner and image forming apparatus - Google Patents

Abstract

The present invention relates to an optical scanning device and an image forming apparatus. The optical scanning device includes: a rotating body having a rotating polygon mirror deflecting a light beam emitted from a light source; a circuit board having a supporting member and a driving unit, the rotating body is rotatably supported by the supporting member, and the driving unit drives A rotating body; a container having a positioning portion for positioning a positioned portion included in the rotating body, the positioned portion protruding from a circuit board, the container housing the rotating body and the circuit board; a second part for fastening the circuit board to the container a fastening part and a second fastening part; and an adjusting part which adjusts the angle of the rotation axis of the rotating body with respect to the container. The first fastening portion and the second fastening portion are arranged such that: when viewed in the axial direction of the rotating shaft of the rotating body, an imaginary straight line leading from the first fastening portion to the second fastening portion on the circuit board passes through the through the rotating body. The adjustment portion is provided on the side of the virtual straight line on which the axis of rotation is provided.

Description

Optical scanning device and image forming device

technical field

The present invention relates to an optical scanning device and an image forming apparatus.

Background technique

Japanese Unexamined Patent Application Publication No. 2008-03231 discloses a scanning optical device in which a side of an optical box facing a circuit board has a through hole, and the circuit board includes a circuit-free portion having neither electronic parts nor circuits, The non-circuit portion is located above the through hole.

Japanese Unexamined Patent Application Publication No. 2008-58353 discloses an optical scanning device in which a correction member is provided between a circuit board and a case, and the correction member can be connected to the case at a position where the correction member does not interfere with the case. The correcting member moves between positions where it contacts the housing and lifts the circuit board in a manner that bends the circuit board.

Contents of the invention

The present invention provides a technique in which the angle of the rotation axis of a rotating body provided with a rotating polygon mirror for deflecting a light beam emitted from a light source is adjusted with high precision.

According to a first aspect of the present invention, there is provided an optical scanning device comprising: a rotating body having a rotating polygon mirror deflecting a light beam emitted from a light source; a circuit having a supporting member and a driving unit a plate, the rotating body is rotatably supported by the supporting member, the driving unit drives the rotating body; a container having a positioning portion for placing the rotating body contained in the rotating body positioned by a positioned portion protruding from the circuit board, the container housing the rotating body and the circuit board; a first fastening portion and a second fastening portion, the first fastening portion and the second fastening portion for fastening the circuit board to the container; and an adjusting portion for adjusting an angle of a rotation axis of the rotating body relative to the container. The first fastening portion and the second fastening portion are arranged such that, when viewed in the axial direction of the rotating shaft of the rotating body, on the circuit board, from the first fastening An imaginary straight line partially leading to the second fastening portion passes through the rotating body. The regulating portion is provided on a side of the virtual straight line on which the rotation shaft is provided.

According to the second aspect of the present invention, the adjusting portion is provided on a side of the circuit board opposite to an incident side of the light beam on the rotating polygon mirror with respect to the virtual straight line.

According to the third and fourth aspects of the present invention, when viewed in the axial direction of the rotation shaft of the rotating body, the rotation shaft is provided at part and the inside of the virtual triangle defined by the regulation part.

According to a fifth aspect of the present invention, there is provided an image forming apparatus, the image forming apparatus comprising: the optical scanning device according to any one of the first to fourth aspects of the present invention, the optical scanning device scans A latent image is formed by applying the light beam to a surface of a latent image carrier charged by a charging unit in a manner; and a developing unit that converts the latent image by supplying a developer to the latent image on the latent image carrier. latent image development.

According to the first aspect of the present invention, the rotation can be adjusted with higher precision than the case in which a virtual straight line leading from the first fastening portion to the second fastening portion is away from the rotating body. The angle of the body's axis of rotation.

According to the second aspect of the present invention, compared with the case in which the adjustment portion is provided on the incident side of the light beam on the rotating polygon mirror with respect to the virtual straight line of the circuit board, when the angle adjustment is performed, the light beam No interference with adjustment tools.

According to the third and fourth aspects of the present invention, it is possible to The vibration generated by the circuit board when the rotating body rotates is reduced.

According to the fifth aspect of the present invention, compared with the case where the image forming apparatus does not include the optical scanning device according to any one of the first to fourth aspects of the present invention, it is possible to suppress the inclination due to the rotation axis of the rotating body. to cause any defective images to appear.

Description of drawings

Exemplary embodiments of the present invention will be described in detail based on the following drawings, in which:

FIG. 1 shows the configuration of an image forming apparatus including an optical scanning device according to an exemplary embodiment of the present invention;

2 is a plan view showing the inside of an optical scanning device according to an exemplary embodiment of the present invention viewed along the axial direction of a rotational shaft of a rotating body;

Fig. 3 shows the optical path of the light beam in the optical scanning device according to the exemplary embodiment of the present invention observed along the axial direction of the rotating shaft;

4 shows an optical path of a light beam in an optical scanning device according to an exemplary embodiment of the present invention viewed along the direction in which the light beam is emitted from a light source;

5 is a plan view of a deflector including a rotating body provided in an optical scanning device according to an exemplary embodiment of the present invention, viewed along the axial direction of a rotating shaft;

Figure 6 is a plan view corresponding to Figure 5 with the deflector removed;

7 is a perspective view of a deflector provided in an optical scanning device according to an exemplary embodiment of the present invention;

Figure 8 is an exploded perspective view corresponding to Figure 7 with the deflector removed;

9A is a perspective view of a first support member or a second support member;

Figure 9B is a perspective view of an adjustment support member;

10A is a front view of the deflector viewed along the X direction, the deflector is in an initial tilt state, in this state, the angle of the rotation axis of the rotating body contained in the deflector has not yet been adjusted;

10B is a front view of the deflector seen along the X direction, the deflector is in a state where the angle of the rotation axis has been adjusted;

11 is a cross-sectional view of a deflector, wherein a protrusion provided on a rotating body of the deflector is fitted in a fitting hole;

Fig. 12 is a plan view of the deflector viewed along the axial direction of the rotating shaft, with the rotating body removed;

Figure 13 is a block diagram of a circuit controlling the deflector;

Fig. 14 shows virtual straight line S1, virtual straight line S2 and virtual triangle R;

Figure 15A shows the deviation of the light beam due to the inclination of the axis of rotation of the rotating body contained in the deflector;

Fig. 15B shows the change of the shape of the scan line due to the inclination of the rotation axis;

Figure 15C shows the change of the image field due to the tilt of the axis of rotation;

Figure 16A schematically shows the circuit board in an initial tilted state;

Fig. 16B schematically shows the circuit board whose angle has been adjusted;

17A is a graph showing the relationship between the inclination of the rotation axis and the protrusion height difference of the boss based on the virtual straight line S1 shown in FIG. 14;

FIG. 17B is a graph showing the relationship between the inclination of the rotation axis and the adjustment amount based on the virtual straight line S1 shown in FIG. 14;

FIG. 17C is a graph showing inclinations of the rotation axis in the X direction and in the Y direction based on the virtual straight line S1 shown in FIG. 14;

FIG. 18A is a graph showing the relationship between the inclination of the rotation axis and the protrusion height difference of the boss based on the virtual straight line S2 shown in FIG. 14;

FIG. 18B is a graph showing the relationship between the inclination of the rotation axis and the adjustment amount based on the virtual straight line S2 shown in FIG. 14;

FIG. 18C is a graph showing inclinations of the rotation axis in the X direction and in the Y direction based on the virtual straight line S2 shown in FIG. 14;

Fig. 19 shows the displacement distribution in the deflector based on the virtual straight line S1 shown in Fig. 14;

Figure 20 shows the displacement distribution in the deflector based on the virtual straight line S2 shown in Figure 14;

FIG. 21 is an exploded perspective view corresponding to FIG. 8 and showing a modification of the exemplary embodiment of the present invention;

FIG. 22A is a front view corresponding to FIG. 10A and showing a modification of the exemplary embodiment of the present invention;

FIG. 22B is a front view corresponding to FIG. 10B and showing a modification of the exemplary embodiment of the present invention; and

Fig. 23 shows the stress distribution applied to the circuit board whose angle has been adjusted.

detailed description

An image forming apparatus according to an exemplary embodiment of the present invention will now be described.

Overall Configuration of Image Forming Apparatus

First, the overall configuration of an image forming apparatus according to an exemplary embodiment of the present invention will be described.

Referring to FIG. 1 , an image forming apparatus 10 includes an image forming section 50 , a paper feeding device 20 that supplies recording paper P to the image forming section 50 , an optical scanning device 100 , and the like. The recording paper P is transported along a transport path 80 provided in the image forming apparatus 10 , and output to a paper output section 12 provided at the top of the image forming apparatus 10 .

The image forming section 50 includes image forming units 32Y, 32M, 32C, and 32K provided corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K). The image forming units 32Y, 32M, 32C, and 32K all have the same configuration, but the colors of toner contained therein are different. Hereinafter, components and devices (including image forming units 32Y, 32M, 32C, and 32K) assigned to components and devices (including the image forming units 32Y, 32M, 32C, and 32K) are represented by reference characters (Y, M, C, and K) corresponding to the respective colors and added to each reference numeral. However, if the members and devices do not need to be distinguished by their colors, the reference characters corresponding to the respective colors are omitted.

The image forming units 32Y, 32M, 32C, and 32K are arranged side by side at intervals in a direction inclined with respect to the horizontal plane. The positions of the image forming units 32Y, 32M, 32C, and 32K become lower in order.

The image forming units 32Y, 32M, 32C, and 32K include respective drum photoreceptors 34Y, 34M, 34C, and 34K as exemplary latent image carriers, respective charging members 36Y, 36M, 36C, and 36K as exemplary charging units, Respective developing devices 38Y, 38M, 38C, and 38K as exemplary developing units, and respective cleaning devices 42Y, 42M, 42C, and 42K.

The developing device 38 develops the electrostatic latent images formed on the surfaces of the respective photoreceptors 34Y, 34M, 34C, and 34K, whereby yellow (Y), magenta (M ), cyan (C), and black (K) colors form a toner image. The electrostatic latent image is formed by the optical scanning device 100 which will be described separately below. Yellow toner, magenta toner, cyan toner, and black toner are supplied from storage containers 40Y, 40M, 40C, and 40K to developing devices 38Y, 38M, 38C, and 38K, respectively.

The image forming section 50 includes a transfer device 60 that transfers yellow (Y), magenta (M), cyan (C) and black (K) colors formed by the respective developing devices 38Y, 38M, 38C and 38K ) onto the recording paper P;

The transfer device 60 includes a belt-type intermediate transfer body 62 as an exemplary transfer medium, yellow (Y), magenta (M), cyan (C) and Toner images of black (K) are transferred to this intermediate transfer body 62 so as to be superimposed on each other. The intermediate transfer body 62 is stretched around a plurality of rollers 64 and rotates in the direction indicated by the arrow V shown in FIG. 1 .

The transfer device 60 includes: roller-type first transfer members 68Y, 68M, 68C, and 68K to be formed on the respective photoconductors 34Y, 34M, 34C, and 34K The toner images of yellow (Y), magenta (M), cyan (C) and black (K) are transferred to the intermediate transfer body 62; the roller-type second transfer member 69, the roller-type second transfer member 69 The printing member 69 transfers the toner images of yellow (Y), magenta (M), cyan (C), and black (K) transferred to the intermediate transfer body 62 to the recording paper P; and the cleaning device 65 , which The cleaning device 65 cleans the surface of the intermediate transfer body 62 .

The paper feeding device 20 includes a container 22 that accommodates a plurality of sheets of recording paper P, a pickup roller 24 that picks up the uppermost recording sheet P among the plurality of sheets of recording paper P accommodated in the container 22 , and conveys the sheet picked up by the pickup roller 24 . A pair of transport rollers 26 for the recording paper P.

The transport path 80 includes a transport path 82 and a reverse transport path 85 . The transport path 82 is a transport path along which the recording paper P supplied from the paper feeding device 20 is transported toward the paper output portion 12 . A pair of registration rollers 84 , the above-mentioned second transfer member 69 , the above-mentioned fixing device 70 , and a pair of paper output rollers 86 are disposed on the conveyance path 82 in order from the upstream side in the conveyance direction of the recording paper P.

The pair of registration rollers 84 feeds the recording paper P to the nip between the intermediate transfer body 62 and the second transfer member 69 according to the timing at which the toner image is transferred to the intermediate transfer body 62 .

The pair of paper output rollers 86 outputs the recording paper P on which the toner image has been fixed by the fixing device 70 to the paper output section 12 . In the case where images are to be formed on both sides of the recording paper P, the pair of paper output rollers 86 rotates in the backward direction opposite to the direction in which the recording paper P is output to the paper output section 12, and thus are fed in the following manner The recording paper P having an image on one side, that is, the trailing end of the recording paper P is guided into the reverse conveying path 85 . A plurality of pairs of conveyance rollers 89 are provided on the reverse conveyance path 85 . The recording paper P having an image on one side is conveyed by the pair of conveying rollers 89 in such a manner that the recording paper P is reversed and then fed again to a position on the upstream side of the pair of registration rollers 84 .

image forming process

The image forming process will now be described.

When the image forming apparatus 10 is activated, pieces of image data on respective colors of yellow (Y), magenta (M), cyan (C), and black (K) are output to the optical scanning device 100 . The optical scanning device 100 emits light beams LY, LM, LC, and LK according to respective pieces of image data. The light beams LY, LM, LC, and LK are applied to the surfaces (peripheral surfaces) of the respective photoreceptors 34 that have been charged by the respective charging members 36 , thereby forming electrostatic latent images on the surfaces of the respective photoreceptors 34 .

The electrostatic latent images formed on the surfaces of the photoreceptors 34 are developed by the respective developing devices 38 , whereby toner images of respective colors are formed on the surfaces of the respective photoreceptors 34 . The toner images of the respective colors on the surface of the photoreceptor 34 are sequentially and multiple-transferred to the intermediate transfer body 62 by the respective first transfer members 68 .

The toner image multi-transferred to the intermediate transfer body 62 is secondarily transferred by the second transfer member 69 to the recording paper P that has been conveyed to the second transfer member 69 . The recording paper P onto which the toner image has been transferred is conveyed to a fixing device 70 . In the fixing device 70 , the toner image is heated and pressed, thereby being fixed on the recording paper P as a fixed image. The recording paper P with a fixed image is output to the paper output section 12 by a pair of paper output rollers 86 .

In the case of double-sided printing to form another image on the other side of the recording paper P (the side without a fixed image), the toner image on the front side of the recording paper P by the pair of paper output rollers 86 is captured by the fixing device 70 After fixing, it is rotated backward, whereby the recording paper P is fed into the reverse conveyance path 85 . Then, after another set of toner images is formed and fixed on the other side of the recording paper P, the recording paper P is output to the paper output section 12 .

optical scanning device

The optical scanning device 100 will now be described.

Referring to FIG. 1, as described above, the optical scanning device 100 applies the light beams LY, LM, LC, and LK in a scanning manner to the respective photoreceptors 34Y, 34M, 34C that have been charged by the respective charging members 36Y, 36M, 36C, and 36K. and 34K, whereby electrostatic latent images are formed on the surfaces of the respective photoreceptors 34Y, 34M, 34C, and 34K.

The optical scanning device 100 includes a housing (optical box) 102 as an exemplary container fastened at a predetermined position in the image forming apparatus 10 . Referring to FIG. 2 , light sources 104Y, 104M, 104C, and 104K are disposed at an inner end of the housing 102 . The light sources 104Y, 104M, 104C, and 104K respectively emit light beams LY for yellow (Y), light beams LM for magenta (M), light beams LC for cyan (C), and light beams LK for black (K). , as shown in Figures 2 and 3.

As mentioned above, components provided for respective colors are identified by reference characters (Y, M, C, and K) representing respective colors added after each reference number, however, if these components do not need to be distinguished by their colors, The reference characters following the respective reference signs are then omitted.

The direction in which the light beam L is emitted from the light source 104 (that is, the direction of the optical axis) is defined as the X direction, the direction perpendicular to the X direction and parallel to the bottom plate 102A of the housing 102 is defined as the Y direction, and the X direction and the Y direction are defined as the Y direction. The direction that is both orthogonal is defined as the Z direction. Although the optical scanning device 100 is actually angled with respect to a horizontal plane as shown in FIG. 1 , for convenience, the optical scanning device 100 is described by defining X and Y directions as horizontal directions and Z direction as a vertical direction. In this exemplary embodiment, the Z direction coincides with the thickness direction of the bottom plate 102A which will be described separately below. The axial direction of the rotating shaft 212 of the rotating body 210 included in the deflector 200 which will be described separately below is adjusted to coincide with the Z direction.

Referring to FIG. 2 , light sources 104Y, 104M, 104C, and 104K are arranged spaced apart in the Y direction and at different positions in the Z direction so that light beams LY, LM, LC, and LK (see FIG. 4 ) do not interfere with each other. In this exemplary embodiment, the distances between the bottom plate 102A and the light sources 104Y, 104M, 104C, and 104K become smaller in order (see also FIG. 4 ).

Referring to FIGS. 2 , 5 and 7 , the deflector 200 is fastened to the bottom plate 102A of the housing 102 of the optical scanning device 100 . The deflector 200 includes a rotating body 210 . The rotating body 210 includes a rotating polygon mirror 204 having a plurality (twelve in this exemplary embodiment) of reflecting surfaces 202 . The rotating body 210 is provided on a circuit board 250 fastened to the bottom plate 102A of the housing 102 . The rotating body 210 is rotated by a drive motor 221 provided on a circuit board 250 to be described below (see FIG. 12 ). The rotating body 210 reflects the light beams L emitted from the respective light sources 104 (see FIG. 2 ), and applies the light beams L to the respective light sources in a manner of scanningly moving the light beams L in the scanning direction (direction corresponding to the axial direction of the photoreceptor 34 ). Photoreceptor 34 (see FIG. 1 ).

Referring to FIGS. 2 and 3 , first lens systems 106Y, 106M, 106C, and 106K are provided on the downstream sides of the respective light sources 104, and the first lens systems 106Y, 106M, 106C, and 106K are provided for respective colors, and each includes a A collimator and the like for collimating a corresponding one of the light beams L emitted from the light source 104 . First reflection mirrors 108Y, 108M, 108C, and 108K are provided on the downstream side of the respective first lens systems 106 . A second reflection mirror 110 is provided on the downstream side of the first reflection mirrors 108Y, 108M, 108C, and 108K. A third reflection mirror 112 is provided on the downstream side of the second reflection mirror 110 . Second lens systems 116A and 116B are disposed between the second mirror 110 and the third mirror 112 . Third lens systems 118A and 118B are disposed between the third mirror 112 and the deflector 200 .

Light beams LY, LM, LC, and LK emitted from light sources 104Y, 104M, 104C, and 104K are transmitted through respective first lens systems 106Y, 106M, 106C, and 106K, and are transmitted by respective first mirrors 108Y, 108M, 108C, and 108K reflects to travel towards the second mirror 110 . The light beam L reflected by the second mirror 110 travels toward the third mirror 112 while being transmitted through the second lens systems 116A and 116B, and is directed by the third mirror 112 toward the rotating body 210 (rotating polygonal mirror) of the deflector 200 . 204) Reflection. The light beam L reflected by the third mirror 112 is transmitted through the third lens systems 118A and 118B and is incident on the rotating polygon mirror 204 of the rotating body 210 of the deflector 200 .

An fθ lens 120 is provided on the downstream side of the deflector 200 (see also FIGS. 5 and 7 ). The four light beams LY, LM, LC, and LK reflected by any one of the reflection surfaces 202 of the rotating polygon mirror 204 enter the fθ lens 120 where the scanning of the light beam L on the respective photoreceptors 34 (see FIG. 1 ) is made The speed of movement is uniform.

Referring to FIG. 4 , on the downstream side of the fθ lens 120 is provided a beam splitting optical system 122 that splits the four light beams LY, LM, LC, and LK and emits the light beams LY toward the photoreceptors 34Y, 34M, 34C, and 34K. , LM, LC and LK. The beam splitting optical system 122 includes a fourth mirror (folding mirror) 124 , fifth mirrors 126A and 126B, sixth mirrors 128Y, 128M, 128C, and 128K, and seventh mirrors 130M, 130C, and 130K.

The four light beams LY, LM, LC, and LK transmitted through the fθ lens 120 are reflected by the fourth mirror 124 . Two light beams LY and LM among the four light beams LY, LM, LC, and LK reflected by the fourth mirror 124 are reflected by the fifth mirror 126A. The light beam LY of the two light beams LY and LM reflected by the fifth mirror 126A is reflected by the sixth mirror 128Y, and travels toward the photoreceptor 34Y. The light beam LM is reflected by the sixth mirror 128M, and is reflected by the seventh mirror 130M to travel toward the photoreceptor 34M.

Two light beams LC and LK among the four light beams LY, LM, LC, and LK reflected by the fourth mirror 124 are reflected by the fifth mirror 126B. Of the light beams LC and LK reflected by the fifth mirror 126B, the light beam LC is reflected by the sixth mirror 128C, and is reflected by the seventh mirror 130C to travel toward the photoreceptor 34C. The light beam LK is reflected by the sixth mirror 128K, and is reflected by the seventh mirror 130K to travel toward the photoreceptor 34K.

Attachment of deflectors and deflectors

The deflector 200 and the attachment of the deflector 200 to the bottom plate 102A of the housing 102 will now be described.

Referring to Figures 5 and 7, the deflector 200 is fastened to the bottom plate 102A of the housing 102 of the optical scanning device (see also Figure 2). As described above, the deflector 200 includes a rotating body 210 including a reflection polygon mirror 204 having a plurality (twelve in this exemplary embodiment) of reflection surfaces 202 . The rotating body 210 is provided on a circuit board 250 fastened to the housing 102 .

The rotating body 210 is rotated about a rotating shaft 212 by a driving motor 221 to be described below. Referring to FIGS. 4 , 8 and 11 , the rotating body 210 has a protrusion 214 as an exemplary positioned portion. The protrusion 214 has a substantially cylindrical shape. A rotation shaft 212 is rotatably supported in this protrusion 214 . In this exemplary embodiment, the axis of the protrusion 214 and the axis of the rotation shaft 212 coincide with each other.

Referring to FIG. 12 , the rotating body 210 (see FIG. 5 and other figures) is rotated by a driving motor 221 including a plurality of driving coils 222 and a plurality of driving magnets (not shown). The plurality of driving magnets are annularly arranged in the rotating body 210 and are alternately magnetized into north and south poles. The driving coil 222 is fastened at a position facing a driving magnet (not shown). The driving coil 222 is connected to a wire pattern provided on the circuit board 250 . An excitation current supplied according to a signal from a Hall element 224 as an exemplary position detector flows through the driving coil 222 . When an excitation current flows through the driving coil 222 , an induced magnetic field is generated between the driving coil 222 and the driving magnet, whereby the rotating body 210 rotates.

In this exemplary embodiment, circuit board 250 includes base member 248 made of a metal plate and phenolic cardboard 246 attached to base member 248 by bonding, caulking, or the like. Electronics and wire patterns are provided on the phenolic cardboard 246 . The integrated circuit 252 and the like are mounted on the upper surface (the side having the wiring pattern) of the circuit board 150 . The integrated circuit 252 includes a constant speed control circuit 254 and a drive circuit 258 , and controls switching of the polarity of the drive coil 222 . Hall elements 224 that detect the position of the rotating body 210 are also mounted on the upper surface of the circuit board 250 .

Referring to FIG. 13 , information on the speed of the rotating body 210 obtained by a signal from the Hall element 224 is fed back to a constant speed control circuit 254 (phase-locked loop) included in an integrated circuit 252 . This information is compared to a reference signal 256 corresponding to the desired number of revolutions. An excitation current for compensating the difference between the two is supplied to the driving circuit 258 as an exemplary driving unit. Thus, the rotating body 210 is caused to rotate at a constant speed.

Referring to FIGS. 5 , 7 and 8 , the circuit board 250 of the deflector 200 has a substantially rectangular plate-like shape when viewed along the axial direction of the rotating shaft 212 of the rotating body 210 . The long side direction of the circuit board 250 corresponds to the X direction (direction of the optical axis of the light source 104 , see also FIG. 2 ). The rotating body 210 is disposed on the side of the circuit board 250 that is closer to the light source 104 (see FIG. 2 ).

The circuit board 250 has: a first fastening hole 262 provided in a corner at an end 263 of the circuit board 250 on the side opposite to the side having the rotating body 210; a fastening hole 264 provided in one of the corners on the side of the circuit board 250 having the rotating body 210 (in a corner diagonal to the first fastening hole 262 ); and An adjustment hole 268 as an exemplary adjustment portion is provided in the other corner of the side of the circuit board 250 having the rotating body 210 .

Referring to FIG. 14 , with respect to the imaginary straight line S1 connecting the first fastening hole 262 and the second fastening hole 264, the adjustment hole 268 is disposed opposite to the incident side of the light beam L on the rotating body 210 (rotating polygon mirror 204). that side. When viewed in the axial direction of the rotating shaft 212 of the rotating body 210 , the rotating body 210 is located on the circuit board 250 such that a virtual straight line S1 passes through (extends on) the rotating body 210 . The rotating body 210 is away from the virtual straight line S1 and faces the adjusting hole 268 . When viewed in the axial direction of the rotation shaft 212 of the rotating body 210 , the rotation shaft 212 is located inside a virtual triangle R defined by the first fastening hole 262 , the second fastening hole 264 and the adjustment hole 268 .

The circuit board 250 also has a substantially U-shaped inner edge cutout 260 (see FIGS. 5 , 7 , 8 and others). The cutout 260 is provided at an end 261 of the circuit board 250 having one side of the rotating body 210 (between the second fastening hole 264 and the adjustment hole 268 ). The cutout 260 is provided in the base member 248 included in the circuit board 250 . The hall element 224 is disposed on a side of the circuit board 250 opposite to the side having the adjustment hole 268 with respect to the imaginary straight line S1 when viewed in the axial direction of the rotation shaft 212 of the rotating body 210 .

Referring to FIGS. 4 , 8 and 11 , the protrusion 214 of the rotating body 210 protrudes from the circuit board 250 and is fitted in the fitting hole 103 provided in the bottom plate 102A of the housing 102 as an exemplary fitting part. Thus, the rotation shaft 212 of the rotating body 210 is positioned in the bottom plate 102A of the housing 102 (at the center of the bottom plate 102A).

Referring to FIG. 6 , FIG. 8 and FIG. 9 , the bottom plate 102A of the housing 102 has a first support member 310 , a second Support member 320 and adjustment support member 330 . 9A and 9B, the first support member 310, the second support member 320 and the adjustment support member 330 each have a cylindrical portion 312, 322 or 332 and a plurality (three in this exemplary embodiment) of bosses 316A to 316C, 326A to 326C, and 336A to 336C. The cylindrical portions 312, 322, and 332 have respective holes 314, 324, and 334 at their centers. Bosses 316A to 316C, 326A to 326C, and 336A to 336C are provided at intervals in the circumferential direction on the upper surfaces of the respective cylindrical portions 312 , 322 , and 332 .

Bosses 316A to 316C, 326A to 326C, and 336A to 336C are provided on the radially outer sides of bearing surfaces 353A, 353B, and 353C of heads 352A, 352B, and 352C of self-tapping screws 350A, 350B, and 350C described below, respectively (see Figure 8 and others).

Referring to FIGS. 6 and 9A , the bosses 316C and 326C of the first support member 310 and the second support member 320 disposed on the side opposite to the side having the adjustment hole 268 with respect to the imaginary straight line S1 (see FIG. 14 ) have The protrusion height (t2) is smaller than the protrusion height (t1) of the other bosses 316A, 316B, 326A, and 326B. Therefore, referring to FIG. 10A , the circuit board 250 is supported with the rotating shaft 212 of the rotating body 210 inclined toward the virtual straight line S1 (details will be described separately below).

Referring to FIG. 9B , the bosses 336A, 336B, and 336C of the adjustment support member 330 have a protrusion height (t3) smaller than that of the bosses 316C and 326C (t2) (t1>t2>t3).

Attachment of the deflector and adjustment of the angle of the rotation axis of the rotating body

A method of attaching and fastening the deflector 200 to the bottom plate 102A of the housing 102 and a method of adjusting the angle of the rotating shaft 212 of the rotating body 210 will now be described.

Referring to FIGS. 10A and 11 , the circuit board 250 of the deflector 200 is placed on the first support member 310 and the second support member 320 on the bottom plate 102A of the housing 102, so that the rotating body 210 protrudes from the circuit board 250. The protrusions 214 of are fitted in the fitting holes 103 (see FIG. 11 ) provided in the bottom plate 102A of the case 102 (see also FIGS. 7 and 8 ).

Subsequently, the self-tapping screws 350A and 350B are respectively inserted into the first fastening hole 262 and the second fastening hole 264 provided in the circuit board 250, and they are respectively screwed into the first supporting member 310 and the second supporting member 320. In the holes 314 and 324 of the cylindrical parts 312 and 322. Subsequently, the self-tapping screw 350C is inserted into the adjustment hole 268 and then inserted into the hole 334 of the cylindrical portion 332 of the adjustment support member 330 .

10A and 16A, the protrusion height (t2) of the bosses 316C and 326C of the first support member 310 and the second support member 320 is smaller than the protrusion height (t1) of the other bosses 316A, 316B, 326A and 326B (see also Figure 9A). Therefore, in the state before the angle adjustment, the circuit board 250 is fastened with the rotation shaft 212 of the rotation body 210 inclined toward the imaginary straight line S1. That is, the circuit board 250 is fastened in a state in which the rotation shaft 212 is inclined with respect to the rotation shaft 212 (see FIGS. 10B and 16B ) whose angle has been adjusted, which will be described separately below. This state is hereinafter referred to as an "initial tilt state".

Subsequently, referring to FIGS. 10B and 16B , the self-tapping screw 350C inserted into the adjustment hole 268 is gradually screwed into the hole 334 . As the self-tapping screw 350C is screwed into the hole 334 , the side of the circuit board 250 having the rotating body 210 with respect to the virtual straight line S1 gradually bends (rotates) around the virtual straight line S1 . When the circuit board 250 is gradually bent, the rotating shaft 212 is gradually tilted away from the virtual straight line S1, so that the axial direction of the rotating shaft 212 becomes closer to the Z direction. In this way, the angle of the rotation shaft 212 of the rotation body 210 is adjusted. In FIG. 10A , FIG. 10B , FIG. 16A and FIG. 16B , the inclination of the rotation axis 212 is shown larger than the actual inclination in order to easily recognize the angle change.

In this exemplary embodiment, self-tapping screws 350C are employed. In this way, the angle is adjusted only in the direction in which the self-tapping screw 350C is screwed into the hole 334 . This angle can be adjusted by loosening the self-tapping screw 350C already screwed into the hole 334 .

Whether or not the angle of the rotation shaft 212 of the rotating body 210 falls within a desired range may be determined in any manner. For example, if each beam L has no stray light (ghost light) entering any of the first lens systems 106 except the one corresponding to the beam L (see FIG. 2 ), then the axis of rotation 212 can be determined The angles are within the expected range.

More specifically, for example, it is assumed that the stray light of the light beam LM enters the first lens system 106C adjacent to the first lens system 106M, and the stray light of the light beam LC enters the first lens system 106M adjacent to the first lens system 106C. . In this case, if the stray lights of the light beams LC and LM no longer enter the first lens systems 106M and 106C, respectively, it is determined that the angle of the rotation axis 212 has fallen within the desired range.

Operation function

Operational functions provided in this exemplary embodiment are now described.

Operation function 1

Referring to FIG. 14 , a virtual straight line S1 leading from the first fastening hole 262 to the second fastening hole 264 passes through the rotating body 210 . Here, a virtual straight line S1 corresponding to the bending center (rotation center) of the circuit board 250 is located near the rotation axis 212 of the rotating body 210 . Therefore, the rate of change of the angle of the rotating shaft 212 of the rotating body 210 becomes gentle with respect to the screwing rate of the self-tapping screw 350C used for angle adjustment. Therefore, the angle of the rotating shaft 212 of the rotating body 210 can be adjusted with high precision.

This exemplary embodiment will be described in more detail below in comparison with a comparative embodiment in which the first fastening hole 262 and the first fastening hole 250 of the circuit board 250 connected by an imaginary straight line S2 extending away from the rotating body 210 and The second fastening hole 266 is fastened, as shown in FIG. 14 . In the comparative embodiment employing the third fastening hole 266 , self-tapping screws are screwed into the third support member 800 (see FIGS. 6 and 8 ). The third support member 800 (see FIGS. 6 and 8 ) has the same configuration as the first support member 310 and the second support member 320 .

Comparison of the screw-in rate with respect to the self-tapping screw 350C in the portion having the rotation axis 212 of the circuit board 250 based on the case of the virtual straight line S1 extending close to the rotation axis 212 and the case based on the virtual straight line S2 extending away from the rotation axis 212 The rate of change (bending) is smaller in the case based on the virtual straight line S1 than in the case based on the virtual straight line S2. That is, the rate of change of the angle of the rotating shaft 212 of the rotating body 210 with respect to the screw-in rate of the self-tapping screw 350C used for angle adjustment is gentler in the case based on the virtual straight line S1 than in the case based on the virtual straight line S2. .

17A to 17C are graphs showing actual changes in the angle of the rotation shaft 212 (in the case based on the virtual straight line S1 ) according to an exemplary embodiment. FIGS. 18A to 18C are graphs respectively corresponding to the graphs shown in FIGS. 17A to 17C , and relate to the comparative embodiment (case based on the virtual straight line S2 ). The numerical symbols -0.02, -0.04 and -0.06 given in the legend all represent the difference (t1 -t2) (see also Figures 9A and 9B).

17A and 18A show the angle of the rotation shaft 212 in the initial tilt state shown in FIG. 10A . 17B and 18B show the inclination of the rotation shaft 212 observed when the circuit board 250 that has been leveled horizontally is displaced by ±0.1 mm by using the self-tapping screw 350C for adjustment. 17C and 18C show the inclination amounts of the rotation shaft 212 in the X direction and the Y direction observed when the self-tapping screw 350C is gradually screwed into the hole 334 .

Compared to the graphs shown in FIGS. 17B and 18B , in the exemplary embodiment, the gradient in the range from -0.1 mm to 0 mm is more gradual. Compared with the graphs shown in FIGS. 17C and 18C , the amount of inclination in the exemplary embodiment (based on the case of the virtual straight line S1 ) does not change substantially in the X direction, but greatly changes in the Y direction, while comparing The amount of inclination in the embodiment (based on the case of the virtual straight line S2 ) varies in both the X direction and the Y direction. That is, the rate of change of the angle of the rotating shaft 212 of the rotating body 210 with respect to the screw-in rate of the self-tapping screw 350C used in angle adjustment is higher in the exemplary embodiment (the case based on the virtual straight line S1 ) than in the comparative embodiment. (Based on the case of the virtual straight line S2), it is gentler.

FIG. 19 shows distribution of displacement of the circuit board 250 caused by angle adjustment according to an exemplary embodiment (based on the case of the virtual straight line S1 ). FIG. 20 shows the distribution of the displacement of the circuit board 250 caused by the angle adjustment according to the comparative embodiment (based on the case of the virtual straight line S2 ). The denser the dots, the greater the displacement. Comparing the distributions in FIG. 19 and FIG. 20 , the displacement of the circuit board 250 caused by the same adjustment amount is smaller in the exemplary embodiment than in the comparative embodiment.

The closer the virtual straight line S1 is to the rotation axis 212 of the rotating body 210 , the more remarkable the above phenomenon is. The virtual straight line S1 may pass through the rotation axis 212 of the rotation body 210 . That is, the rotation axis 212 may be located on the bending (rotation) center. As can be seen from FIGS. 10A , 10B, 16A, and 16B, the side of the circuit board 250 opposite to the side having the adjustment hole 268 with respect to the virtual straight line S1 is substantially not bent. Therefore, a configuration in which the virtual straight line S1 is closer to the adjustment hole 268 than the rotation axis 212 of the rotating body 210 is unacceptable. That is, it is unacceptable that the rotation axis 212 is located at a position of the circuit board 250 farther from the adjustment hole 268 than the virtual straight line S1.

Operation function 2

Referring to FIG. 14 , the adjustment hole 268 of the circuit board 250 is located on the side of the virtual straight line S1 opposite to the incident side of the light beam L on the rotating polygon mirror 204 . Thus, when the angle of the rotation axis 212 is adjusted by screwing the self-tapping screw 350 for adjustment into the hole 334, the light beam L does not interfere with the tool used for the adjustment (the tool does not block the light beam L). Therefore, the work efficiency of adjusting the angle of the rotation axis 212 of the rotating body 210 by using the light beam L is improved. Thus, the angle of the rotation shaft 212 is adjusted with high precision.

Operation function 3

Referring to FIG. 14 , the rotating shaft 212 of the rotating body 210 is located inside a virtual triangle R defined by the first fastening hole 262 , the second fastening hole 264 and the adjustment hole 268 . The vertices of the area of the circuit board 250 surrounded by the imaginary triangle R are fastened, and thus have higher rigidity than the area of the circuit board 250 having the cantilever structure outside the imaginary triangle R. In this way, compared with the case where the rotating shaft 212 of the rotating body 210 is located outside the virtual triangle R, the vibration of the circuit board 250 generated when the rotating body 210 rotates can be reduced.

Operation function 4

Referring to FIG. 10A , the circuit board 250 is preset such that the rotation axis 212 of the rotating body 210 is inclined toward the virtual straight line S1 (so as to be in an initial inclined state). In this state, tapping screws 350C are screwed into the holes 334, and the circuit board 250 is bent as shown in FIG. 10B. As a result, the angle of the rotation axis 212 is inclined in a direction away from the virtual straight line S1. Since the angle adjustment using the tapping screw 350C is performed in one direction, the angle of the rotation shaft 212 of the rotating body 210 is adjusted with high precision.

Operation function 5

Hall element 224 is disposed on the side of circuit board 250 opposite to the side having adjustment hole 268 with respect to imaginary straight line S1 (see FIG. 12 ) when viewed in the axial direction of rotation shaft 212 of rotary body 210 . If the circuit board 250 is bent, the displacement amount of the side opposite to the side having the adjustment hole 268 of the circuit board 250 is smaller than the displacement amount of the side of the circuit board 250 having the adjustment hole 268, that is, the Hall element 224 The position change with respect to the rotating body 210 is small. Therefore, the velocity information (signal) emitted from the Hall element 224 is less degraded while maintaining the accuracy of detecting the position of the rotating body 210 . In this way, the angle of the rotating body 212 is adjusted while maintaining the accuracy of detecting the position of the rotating body 210 .

Operation function 6

The circuit board 250 has a cutout 260 with a substantially U-shaped inner edge (see also FIGS. 5 , 7 , 8 and others). The cutout 260 is provided at an end 261 of the circuit board 250 on the side having the rotating body 210 (between the second fastening hole 264 and the adjustment hole 268 ). In this way, if the circuit board 250 is bent when the angle of the rotation shaft 212 is adjusted, stress is concentrated around the cutout 260 , thereby reducing stress applied to other portions of the circuit board 250 excluding portions around the cutout 260 . Additionally, in this exemplary embodiment, cutout 260 is provided in base member 248 included in circuit board 250 . Therefore, the deformation of the phenolic cardboard 246 having electronic parts and wire patterns is effectively reduced. As a result, stress applied to these electronic parts and wiring patterns is effectively reduced.

In addition, since the stress is concentrated around the cutout 260 , the rate of change in the amount of bending of the circuit board 250 with respect to the rate of screwing in of the self-tapping screw 350C is reduced. Thus, the angle of the rotation shaft 212 is adjusted with higher precision than in the case where the cutout 260 is not provided.

Now, the distribution of stress applied to the circuit board 250 after the angle adjustment will be described.

FIG. 23 shows the distribution of stress applied to the base member 248 of the circuit board 250 after the angle adjustment. The denser the dots, the greater the stress. As can be seen from FIG. 23 , stress is concentrated around the cutout 260 provided at the end 261 (of the base member 248 ) of the circuit board 250 . In addition, the stress applied to the side (of the base member 248 ) of the circuit board 250 opposite to the side having the adjustment hole 268 is smaller than the stress on the side having the adjustment hole 268 .

Operation function 7

Referring to FIG. 6 and FIG. 9A , the protruding heights of the bosses 316C and 326C (which are respectively disposed on the side of the first support member 310 and the second support member 320 farther from the adjustment hole 268 (compared to the virtual straight line S1 )) ( t2 ) is smaller than the protrusion height ( t1 ) of the other bosses 316A, 316B, 326A, and 326B. In this way, the circuit board 250 is supported with the rotating shaft 212 of the rotating body 210 inclined toward the imaginary straight line S1. Therefore, if the mold used to form the housing 102 includes portions corresponding to the first support member 310 and the second support member 320 or the bosses 316C and 326C nested therein, the entire mold used to form the housing 102 would be In the case of a die, the protrusion heights of the bosses 316C and 326C can be changed. That is, the angle of the rotation shaft 212 to be inclined toward the virtual straight line S1 can be adjusted in advance without changing the entire mold for forming the housing 102 . Therefore, even if the characteristics or other specifications regarding the inclination of the deflector's rotation axis vary greatly, the entire mold used to form the housing 102 does not need to be replaced, for example, in the case of employing a different specification of the deflector.

Operation function 8

Referring to FIGS. 9B , 10A, and 10B, the adjustment support member 330 has bosses 336A, 336B, and 336C whose protruding height (t3) is smaller than that of the bosses 316C and 326C (t2). In this way, the rotation shaft 212 can be adjusted over a large angular range using the self-tapping screw 350C. Furthermore, assuming that the Y direction and the X direction are a horizontal plane, the portion of the circuit board 250 having the adjustment hole 268 can move toward the bottom plate 102A beyond the horizontal plane. Therefore, the rotation shaft 212 can be adjusted over a large angular range.

Operation function 9

Referring to FIG. 9A, bosses 316A to 316C, 326A to 326C and 336A to 336C are provided on the outsides of bearing surfaces 353A, 353B and 353C of heads 352A, 352B and 352C of self-tapping screws 350A, 350B and 350C, respectively (see FIG. 8 and other diagrams). This configuration reduces the possibility that the rotating shaft 212 may be tilted due to contact between the bearing surfaces 353A, 353B, and 353C and any of the bosses 316A-316C, 326A-326C, and 336A-336C.

Other operating functions

As described above, since the angle of the rotating shaft 212 of the rotating body 210 can be adjusted with high precision, the following operation functions are also provided.

Referring to FIG. 15A , since the angle of the rotation axis 212 of the rotating body 210 can be adjusted with high precision, deviation (offset) of the light beam L is reduced.

For example, in the comparative embodiment in which the angle adjustment accuracy of the rotation shaft 212 of the rotating body 210 is low and the inclination of the rotation shaft 212 is large, the path deviation (shift) of the light beam L' is large. This light beam L' has a possibility of impinging on the fourth mirror 124 included in the beam splitting optical system 122. In this case, it is necessary to increase the size of the fourth mirror 124 .

In contrast, in the exemplary embodiment in which the angle of the rotation shaft 212 of the rotating body 210 can be adjusted with high precision, the deviation (offset) of the path of the light beam L is reduced. Therefore, the size of the fourth mirror 124 included in the beam splitting optical system 122 can be reduced.

Furthermore, since the angle of the rotating shaft 212 of the rotating body 210 can be adjusted with high precision, variations in characteristics such as the shape of the scan line and the curvature of the magnetic field are reduced.

Specifically, referring to FIG. 15B , in a comparative embodiment in which the angle adjustment accuracy of the rotation axis 212 of the rotating body 210 is low and the inclination of the rotation axis 212 is large, the scanning line G' may be due to the relative rotation of the beam L' The incident angle of the normal line of the polygon mirror 204 changes and bends.

In contrast, in the exemplary embodiment in which the angle of the rotating shaft 212 of the rotating body 210 can be adjusted with high precision, the bending of the scanning line G is suppressed because the angle of the light beam L relative to the rotating polygon mirror 204 is reduced. The change in the angle of incidence of the normal.

In addition, referring to FIG. 15C , in the comparative embodiment in which the angle adjustment accuracy of the rotation shaft 212 of the rotating body 210 is low and the inclination of the rotation shaft 212 is large, because the incident position and angle of the light beam L' on the fθ lens 120 changes, so the position of the image field and thus the position of the image drawn by the light beam L' formed on the photoreceptor 34 may shift, as indicated by arrows J1 and J2.

In contrast, in the exemplary embodiment in which the angle of the rotation shaft 212 of the rotating body 210 can be adjusted with high precision, variations in the incident position and angle of the light beam L on the fθ lens 120 are reduced. As a result, variations in the position of the image field and the drawing position of the image formed by the light beam L on the photoreceptor 34 are reduced.

Modification

A modified example of the exemplary embodiment will now be described.

In this modification, referring to FIGS. 21 , 22A, and 22B, the circuit board 250 and the corresponding bearing surfaces 353A, 353B, and 353C of the heads 352A, 352B, and 352C of the self-tapping screws 350A, 350B, and 350C are inserted. Ring-shaped rubber members 400A, 400B, and 400C are provided as exemplary elastic members.

By interposing the rubber members 400A, 400B, and 400C between the circuit board 250 and the support surfaces 353A, 353B, and 353C, errors (deviations) in insertion angles of the self-tapping screws 350A, 350B, and 350C are reduced. As a result, angular deviation of the rotating shaft 212 of the rotating body 210 is reduced.

Other exemplary implementations

The present invention is not limited to the exemplary embodiments described above

For example, although the above-described exemplary embodiment refers to the case of using the self-tapping screw 350C, the present invention is not limited to this case. The adjustment support member 330 may have threads pre-set therein or may be provided with a helical insert for a normal screw. In this case, the angle may be adjusted by loosening a screw screwed into the adjustment support member 330 .

The configuration of the image forming apparatus is also not limited to the configuration described in the above exemplary embodiments, and various other configurations are also acceptable. Also, it is obvious that the present invention can be implemented in various other ways within the scope of the present invention.

The foregoing description of exemplary embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and changes will be apparent to those skilled in the art. The embodiments were chosen and described in order to better explain the principles of the invention and its practical application, thereby enabling those skilled in the art to understand the invention for various embodiments and with various aspects as are suited to the particular use contemplated. kind of modification. The scope of the invention is defined by the appended claims and their equivalents.

Claims (5)

1. An optical scanning device, the optical scanning device comprising: a rotating body having a rotating polygon mirror deflecting a light beam emitted from a light source and a rotating shaft supporting the rotating polygon mirror; a circuit board having a support member by which the rotating body is rotatably supported and a driving unit which drives the rotating body; a container having a positioning portion for positioning a positioned portion included in the rotating body, the positioned portion protruding from the circuit board, the container accommodating the rotating body and the the circuit board; a first fastening portion and a second fastening portion that fasten the circuit board to the container; and an adjusting portion for adjusting an angle of the rotation axis of the rotating body relative to the container, Wherein, the first fastening portion and the second fastening portion are arranged such that: when viewed in the axial direction of the rotating shaft of the rotating body, on the circuit board, from the first an imaginary straight line leading from the fastening portion to the second fastening portion passes through the rotating body, and Wherein, the adjusting portion is arranged on the side of the virtual straight line on which the entire rotation axis is arranged, so that the rotation axis is completely located on the same side of the virtual straight line on which the adjusting portion is located. 2. The optical scanning device according to claim 1, wherein the adjusting portion is provided on the side of the circuit board opposite to the incident side of the light beam on the rotating polygon mirror with respect to the virtual straight line. side. 3. The optical scanning device according to claim 1 , wherein, when viewed in the axial direction of the rotation shaft of the rotating body, the rotation shaft is disposed between the first fastening portion, the second fastening portion, The inner side of the imaginary triangle defined by the two fastening portions and the adjusting portion. 4. The optical scanning device according to claim 2 , wherein, when viewed in the axial direction of the rotation shaft of the rotating body, the rotation shaft is disposed between the first fastening portion, the second fastening portion, The inner side of the imaginary triangle defined by the two fastening portions and the adjusting portion. 5. An image forming apparatus comprising: The optical scanning device according to any one of claims 1 to 4, which forms a latent image by applying the light beam to a surface of a latent image carrier charged by a charging unit in a scanning manner; and A developing unit that develops the latent image on the latent image carrier by supplying a developer to the latent image.